Effect of aflibercept in insufficient responders to prior anti-VEGF therapy in neovascular AMD

PURPOSE: Evaluation of three aflibercept injections at 4-week intervals in patients with neovascular AMD showing an “insufficient anatomic response” to prior anti-VEGF therapy with ranibizumab or bevacizumab. METHODS: The retrospective analysis included 96 eyes that had received at least three intravitreal 0.5 mg ranibizumab or 1.25 mg bevacizumab injections over a period of no more than 4 months prior to switching to aflibercept. In addition, the selected eyes had to have evidence of persisting or increasing sub- or intraretinal fluid, observed in optical coherence tomography (OCT). All patients received a loading dose of three intravitreal 2 mg aflibercept injections at 4-week intervals. Evaluation included central retinal thickness (CRT) and maximum pigment epithelium (PED) height measured by spectral domain OCT and best-corrected visual acuity (BCVA) prior to the switch of therapy and 4 weeks after the third aflibercept injection. RESULTS: A significant reduction of mean CRT (−39 μm; p < 0.001) and maximum PED height (−46 μm; p < 0.001) as found 4 weeks after the third aflibercept injection. Eighty-two out of 96 eyes (85 %) had a PED just prior to switching to aflibercept. There was an improvement in BCVA of 1.9 letters 4 weeks after the last aflibercept injection; the vision gain, however, did not reach statistical significance (p = 0.061). The further analysis did not show any correlation of the change in CRT, maximum PED, and BCVA with the number of prior anti-VEGF treatments. CONCLUSION: Retinal edema and PEDs regressed significantly after switching to aflibercept in patients insufficiently responding to prior therapy with ranibizumab or bevacizumab. No correlation could be found with regard to the number of prior treatments

Clinical pharmacology of intravitreal anti-VEGF drugs

Clinical efficacy of intravitreal anti-VEGF drugs has been widely demonstrated in several angiogenesis-driven eye diseases including diabetic macular edema and the neovascular form of age-related macular degeneration. Pegaptanib, ranibizumab, and aflibercept have been approved for use in the eye, whereas bevacizumab is widely used by ophthalmologists to treat patients "off-label". These drugs are active in the nanomolar to picomolar range; however, caution is required when establishing the rank order of affinity and potency due to in vitro inter-experimental variation. Despite the small doses used for eye diseases and the intravitreal route of administration may limit systemic side effects, these drugs can penetrate into blood circulation and alter systemic VEGF with unknown clinical consequences, particularly in vulnerable groups of patients. Clinical pharmacokinetics of ocular anti-VEGF agents should therefore be taken into account when choosing the right drug for the individual patient. The gaps in current understanding that leave open important questions are as follows: (i) uncertainty about which drug should be given first, (ii) how long these drugs can be used safely, and (iii) the choice of the best pharmacological strategy after first-line treatment failure. The current review article, based on the information published in peer-reviewed published papers relevant to anti-VEGF treatments and available on the PubMed database, describes in detail the clinical pharmacology of this class of drugs to provide a sound pharmacological basis for their proper use in ophthalmology clinical practice